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Graham Robson

By the late 1930s Mercedes-Benz was fast running out of new engineering fields to conquer. The company was already the most influential car and truck building concern in Germany. It was an acknowledged automotive technical innovator, it was a pioneer in diesel-engine vehicle installations, it was the first to build luxurious road cars which could exceed 100 mph, and it was already building some of the world’s most successful racing cars. It was also ready to build some of the world’s best and most powerful aircraft engines. Maybe, just maybe, there was little else to achieve, at least for the moment.

By the late 1930s Mercedes-Benz was fast running out of new engineering fields to conquer. The company was already the most influential car and truck building concern in Germany. It was an acknowledged automotive technical innovator, it was a pioneer in diesel-engine vehicle installations, it was the first to build luxurious road cars which could exceed 100 mph, and it was already building some of the world’s most successful racing cars. It was also ready to build some of the world’s best and most powerful aircraft engines. Maybe, just maybe, there was little else to achieve, at least for the moment.

An audacious new goal

That was when, probably for the very first time, an outsider burst upon the scene who believed that he could add to those achievements. Why not, independent racing driver Hans Stück thought, conceive an individual machine, get Daimler-Benz to back his grand design, and have a go at breaking the World Land Speed Record? That field seemed to have been controlled by British interests in the previous decade, but perhaps they could be beaten.

That was the big idea, but in 1936 Stück faced several seemingly insuperable obstacles in making his dream work, especially as his current links were with Auto-Union, and not with Mercedes-Benz. Another was that he knew that his projected car would need a colossally powerful engine to urge it beyond 300 mph, and a third challenge was that there seemed to be no such suitable German engine in existence.  Finally, Stück found it difficult to get his pipe dream turned into a viable engineering possibility.

Overcoming obstacles and closing the deal

Stück, they say, had already contacted Mercedes-Benz’s Alfred Neubauer and told him that he could organize everything, but that it would cost the equivalent of about $300,000. Neubauer, realizing that Stück, though a good talker, had little money to back him, was ready to turn him down when Stück apparently commented that of course he could get Ferdinand Porsche to do the design work for him!

The Porsche name carried a long list of pros and cons. On the pro side was the fact that Porsche had been technical director of the Mercedes-Benz company for some years in the late 1920s, was already well-respected for the work his modern consultancy concern was doing for the industry; Mercedes-Benz was about to build a whole series of VW Beetle prototypes for him. On the con side was the fact that it was the Porsche Bureau that had designed the mid-engined Auto-Union race cars of the early-to-mid 1930s. These were deadly rivals of the Silver Arrows in Grand Prix racing, so there was an element of sleeping with the enemy in motorsports.

Somehow Stück edged his way towards a deal. First of all, he persuaded Mercedes-Benz to let him have the use of high-tuned prototype DB601 inverted V-12 aircraft engines. These were equipped with a pioneering Bosch fuel-injection system, and were to be kept under the control of Mercedes-Benz. Next he persuaded Porsche to undertake a serious design study (which Mercedes-Benz later funded). More important in many ways, he arranged for this new car to be raced along the brand-new autobahn/race track/straightaway at Dessau, which was already allocated to both Auto Union and Mercedes-Benz for less extreme sprint record purposes.

Building the perfect beast

Once agreed, work began at high speed, not only concentrated on the overall layout of the new car, but on how to get enough power from the DB601 engine. By military standards, the DB601 had all started rather modestly, at 33.9 liters and perhaps 1,000 bhp. That may sound like plenty of power, but Stück reckoned that he would need at least 2,500 bhp to ensure that the car could reach its original design top speed of 342 mph.

This was a huge problem, but an equally large obstacle was, quite literally, large. For here was an engine that was no less than 80 inches long, and weighed 1,650 pounds. Not that this terrified the Porsche Bureau, who were used to tackling anything that the client required. Accordingly the detail concept and then the design were developed at phenomenal speed. The scheme was finalized in January 1937, it gained approval, and was designated Type T80 in March of that year. That was a Porsche number, and Mercedes-Benz never gave it a W designation. The first detail drawings for castings followed in July 1937.

In the meantime, the general layout soon began to look familiar to all those who had watched the Mercedes-Benz’s rival Grand Prix car, the Auto Union (also inspired by Porsche), evolve in recent years. The T80 was a mid-engined machine with a sturdy chassis frame. Apart its colossal dimensions and the streamlined body shell, the major chassis evolution was that this car was a six-wheeler, the twinned rear wheels being inter-connected behind the engine by a solid steel shaft.

In view of the need to be as aerodynamically slippery as possible, the single-seater body shell received the most attention in 1937 and 1938. Naturally it was a very large car; twenty-seven feet (27 feet) long. All the running gear and the six wheels were covered by the Duralumin skin panels. Front and rear tracks were very slim indeed, measuring 51.2 inches and 52 inches respectively. The  T80 was no more wide than a modern compact car today, but the body shell had to cover the massive wheels and tires, which were 32 inches in diameter with 7.00-section Continental tires.

The truly remarkable aerodynamic feature, however, was that the body style incorporated wings on each side, approximately amidships, which were no less than 29 inches wide, and were set at a slight negative angle of attack. Wind-tunnel testing of models confirmed that the desing provided a modicum of downforce at higher road speeds. Amazingly, after a great deal of work had gone into refining the car’s shape, it ended up with a remarkably low drag coefficient (Cd) of only 0.18, which gave this 6,400-pound monster a chance of reaching the outright record that meant so much to Stück.

All this was very encouraging to the close-knit team of visionaries who worked steadily on the gradual build-up of the car. Costs continued to rise, but the major problem was that the available engine horsepower from the DB601 unit continued to lag well behind the figures Porsche forecast would be needed to secure the record. Porsche, which had originally insisted that 2,500 brake horsepower was needed, eventually had to accept that the available output for an already heavily modified D601 engine was 2,200 bhp.

Competition heats up

Every week of 1937 and 1938 brought further challenges, not only in the fight to gain enough power, but in matching what was happening out in the wide world. The fact is that by the time the T80 design was being finalized, two rich British enthusiasts, Captain George Eyston and John Cobb, had also completed new aero-engined leviathans, and were gradually pushing up the record figure higher and higher on the Bonneville Salt Flats in the United States.

Originally it was in 1937 that Eyston’s twin-Rolls-Royce-engine Thunderbolt lifted the record to 311.4 mph, while a year later both Thunderbolt, and a sleek new twin Napier Lion-engined car, titled the Railton Mobil Special, returned to Bonneville, and pushed the mark up to 345 mph in the Thunderbolt, and finally to 357.5 mph in the Railton. Every time a British car achieved a higher figure, Mercedes-Benz had to raise its own sights, originally from 342 mph, and by 1939 to no less than 373 mph. Even this, if achieved in practice, would only be marginally higher than the British had already chalked up, so a further enhancement might have been needed.

This was an on-going problem to Mercedes-Benz, for there was really no question of a major redesign of what was already becoming an expensive project. They were determined to complete and campaign the T80 as it had originally been conceived. The car could only be powered by just one, not two, DB600-family aero engines. These engines were now entering serious squadron service with the German Luftwaffe in fighter aircraft such as the Messerschmitt Bf109.

More power was needed

As far as Mercedes-Benz was concerned, this was a magnificent power unit for military use, but at first there was serious lack of peak power for its installation in the T80. The production-standard DB601 produced 1,085 bhp at first, a figure that was readily pushed up to1,455 bhp. But for the T80, this was still not nearly enough.

Their solution, which could not yet be validated by actual in-car performance, was to persuade the military authorities to release a prototype example of the fearsomely advanced DB603 engine. This was a 44.5-liter monster that would produce up to 2,000 bhp in production military form. The new engine was similar in outside dimensions to the DB601, but considerably heavier. As set to be used in the T80, this new unit might have developed 2,800 bhp, which should have been sufficient.

Even so, it still beggars belief that in 1936 the designers had been assured that the DB601 weighed only 1,275 pounds, yet the prototype DB603 suggested for use in 1939 weighed no less than 1,778 pounds. That was an increase of more than 500 pounds in the three years since the T80 project had been born.

Time was running out

At this point, it would be easy to say that too many top-ranking managers began to lose their touch with reality. By mid-1939 the world was about to inflame into war, while the T80 car itself was still not complete or ready to run under its own power. The engine/transmission installation was still provisional and it was far from certain that the car would ever reach, let alone surpass, the figures already set by the British contestants. The proposed site for the record attempt was to be a specially-constructed section of autobahn highway at Dessau, north of Leipzig. The road was only marginally long enough for the car to accelerate from rest to top speed before the measured mile was reached.

So why not send the car to the Bonneville Salt Flats (which were much more spacious), to join in a joust against the Brits? Apparently there were three major reasons; one was that national German pride suggested that the attempt should be held on native soil, another was that the team was still not yet convinced that it could beat the Brits in a straight fight and they did not wish to demonstrate this in public. Third, though it was never publicly spelled out, was that the international situation had changed to much that they had to consider the fact that a prestige German machine like this might immediately be interned if and when war broke out. Its still-secret engine might have been stripped and examined, and it might never get back to its homeland.

What might have been

In the summer of 1939 the definitive DB603 power unit had been craned into position. Final assembly took place in October, and although the engine was started up, the car itself was never put on the road or test track to be driven. The plan was that the T80 would first turn a wheel at the end of the year and a record attempt was pencilled in for early in 1940.

But war had broken out on the first of September 1939, and Mercedes-Benz was soon put on a military footing. The DB603 was repossessed for urgent military testing, and the single T80 was partly stripped out and stored at a tiny location called Karnten in southern Austria, where it stayed for the next five tumultuous years.

At that time, the very existence of the T80 was still not known to other nations, so it was a real surprise when what had become a very down-at-heel and somewhat battered machine was finally liberated and returned to Stuttgart. Although later stripped out, examined, and analysed by the occupying American forces and by Mercedes-Benz engineers themselves, nothing seems to have been done to make it moveable. Of course, no attempt was ever made to discover whether it was likely to live up to its theoretical promise.

In modern times, the main elements of the rolling chassis were put into store in museum premises not far from Stuttgart itself, and the body shell, on a mock-up chassis frame, with wheels, was put on display within the Mercedes-Benz museum.

How fast would the T80 have been? No one knows. Hans Stück never got a chance to find out, and this land speed record vehicle remains as one of very few Mercedes-Benz projects which did not reach the planned end of its intended career.